In preparing silver halide photographic materials, coloration of photographic emulsion layers and other hydrophilic colloid layers is often effected for the purpose of absorbing lights falling within a particular wavelength range.
If it is necessary to control the spectral composition of the light to penetrate into photographic emulsion layers, a colored layer is provided on the support more remotely from the support than photographic emulsion layers. The colored layer is called a filter layer. In the case of a multi-layered color photographic material having plural photographic emulsion layers, the filter layer may be positioned in the intermediate between them.
For the purpose of preventing blur of images to be caused by re-penetration of the light as once scattered during or after passing through photographic emulsion layers and reflected on the interface between the emulsion layer and the support or on the surface of the photographic material opposite to the emulsion layer, into the photographic emulsion layers, or for the purpose of preventing such halation, a colored layer may be provided between the photographic emulsion layer and the support or on the surface of the support opposite to the photographic emulsion layer. The colored layer is called an anti-halation layer. In the case of a multilayered color photographic material having plural photographic emulsion layers, the anti-halation layer may be provided in the intermediate between the respective layers.
For the purpose of preventing lowering of the image sharpness to be caused by scattering of light in photographic emulsion layers (the phenomenon is generally called "irradiation"), coloration of photographic emulsion layers is often effected.
The layers to be colored for the purpose are hydrophilic colloid layers and, in general, dyes are incorporated into the layers so as to color them. The dyes need to satisfy the following conditions.
(1) They have a pertinent spectral absorption in accordance with the use and the object.
(2) They are photochemically inactive. That is to say, they do not have any harmful influences on the chemical properties of silver halide photographic emulsion layers. For example, they do not lower the sensitivity of the emulsion layers, they do not cause latent image fading and they do not cause fogging.
(3) They are decolored or dissolved out in the step of photographic processing or rinsing so that they do not leave any harmful coloration on the processed photographic materials.
(4) They do not diffuse from the layer as dyed with them to any other layers.
(5) They have an excellent time-dependent storage stability in solutions or in photographic materials and are neither discolored nor faded during storage.
In particular, where the colored layer is a filter layer or it is an anti-halation layer to be positioned on the same surface of the support as that having photographic emulsion layers, it is often necessary that such a filter layer or anti-halation layer only is selectively colored in such a way that coloration of the layer does not substantially extend to any other layers. This is because, if not, not only the colored filter layer or anti-halation layer would have any harmful spectral effect on other layers but also the effect of the intended filter layer or anti-halation layer would be lowered. However, when the dye-added layer is brought into contact with any other hydrophilic colloid layers while they are still wet, a part of the dye in the former layer would often diffuse to the latter layers. In order to prevent such diffusion of dyes, various efforts have hitherto been made.
For instance, a method of incorporating a hydrophilic polymer as charged oppositely to the dissociated anionic dye into a layer as a mordant agent along with the dye so that the dye is localized to a particular layer because of the interaction between the polymer and dye molecule is illustrated in U.S. Pat. Nos. 2,548,564, 4,124,386 and 3,625,694.
A method of dyeing a particular layer with dye-adsorbed fine metal salt grains is illustrated in U.S. Pat. Nos. 2,719,088, 2,496,841 and 2,496,843 and JP-A-60-45237 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
A method of dyeing a particular layer with a water-insoluble dye solid is illustrated in JP-A-55-120030, JP-A-56 12639, JP-A-55-155350, JP-A-55-155351, JP A-63-27838, JP-A-63-197943 and JP-A-52-92716, European Patents 15601, 276566, 274723, 323729 and 299435 and PCT 88/04794.
However, even though such improved methods are employed, there are still various problems. Precisely, dyes are often diffused in the dye-fixed layer; the decoloring speed during development is often low; and where the conditions of processing photographic materials are changed, for example, by employing rapid processing system, employing modified processing solution compositions or employing modified photographic emulsion compositions, the decoloring mechanism could not always sufficiently be displayed.